Vacuum sheet control system



Oct. 19, 1965 R. TAYLOR, JR 3,212,775

VACUUM SHEET CONTROL SYSTEM Filed Nov. 5, 1962 5 Sheets-Sheet 1 INVENTOR.

RUEL E. TAYLOR, IR.

ATTORNEYS Oct 1965 R. E. TAYLOR, JR

VACUUM SHEET CONTROL SYSTEM 3 Sheets-Sheet 2 Filed Nov. 5, 1962 MGR m N? 01 W @N w m m o 0 I m a o E R m m vm w M J y k. u mm mm MN mm Y B NQE m mm Oct. 19, 1965 R. E. TAYLOR, JR 3,212,775

VACUUM SHEET CONTROL SYSTEM Filed Nov. 5, 1962 3 Sheets-Sheet 3 FIG4 mm if m IN VENTOR.

RUEL E. TAYLOR,

ATTORNE United States Fatent C) 3,212,775 VACUUM SHEET CONTROL SYSTEM Rue] E. Taylor, Jr., Windham, Maine, assignor to S. D. Warren Company, Boston, Mass, a corporation of Massachusetts Filed Nov. 5, 1962, Ser. No. 235,299 Claims. (Cl. 271-74) This invention relates to method and apparatus for the control of flexible sheets while in motion. The method and apparatus provides for the temporary corrugation of a traveling sheet with the corrugations extending in the direction of travel with the extent of the corrugation being sufficient to stiffen the sheet appreciably for projection without support for a substantial distance beyond the end of the corrugating means thereby permitting handling of the flexible sheet in a satisfactory manner in situations which heretofore have presented some ditficulty.

The present invention will be described particularly with reference to an overlap conveyor for sheets of thin paper of relatively large size. In conventional overlap conveyors for paper sheets, a high speed and a low speed conveyor are provided in succession with the low speed conveyor running somewhat below the extended path of the high speed conveyor run. Sheets which emerge from the end of the high speed conveyor run are thus projected over the low speed conveyor, and upon release fall upon the low speed conveyor and the previous sheets which have been delivered thereto to form the overlapped stream of sheets. The degree of overlap is determined by the relative dimensions of the conveyors and the speeds at which they operate. It will be apparent that the successful operation of such an arrangement depends upon the ability of the high speed conveyor to project the head end of the sheet free of any material support over the established stream of overlapped sheets on the low speed conveyor without having the head end of the sheet fall to a point where it will collide with any tail ends of sheets in the stream on the low speed conveyor. While this environment provides one suitable application for the present invention, it will be understood that the invention may be applied to other and different flexible sheet transport systems and, hence, is not limited specifically to use in an overlap conveyor combination.

Prior art arrangements for the control of flexible sheets have involved various arrangements for the application of air pressure and suction or suitable control of the head end of the sheet by various means. Other arrangements have actually attempted to produce a satisfactory temporary corrugation of a flexible sheet while it is traveling through a machine by the use of corrugating rolls having mating lands and grooves through which the paper passes mechanically to form corrugations therein in the direction of travel. None of these prior art arrangements has provided a satisfactory solution for flexible sheet transport especially in high speed machines where the amount of stiffening required to project a large flexible sheet is considerable. The attempts to achieve this corrugation by mechanical means have resulted in damage to the sheet or in the case of head end gripping of the sheet a severe limitation on the speed of operation.

It is a principal object of the present invention to provide method and apparatus for the temporary corrugation of flexible sheets in a manner which automatically provides the requisite stiffening of the sheet for projection of the sheet to a subsequent point in the flow path for the sheet by the application of differential air pressure across the sheet at laterally spaced longitudinal strips on the sheet in a manner which produces the desired longitudinal corrugation.

A feature of the invention is the provision of a transport for the sheet to be corrugated which cooperates with the vacuum corrugation action which is applied to the sheet by feeding the sheet laterally an amount required to supply the material to build up the corrugations as the sheet flows in its normal longitudinal path through the machine thereby developing the corrugated condition in a stable manner without damage to the sheet from undue stresses being applied or chafing resulting from the drawing of the sheet under stress across a supporting member.

Other objects and features of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view looking down from above showing a high speed tape conveyor delivering a corrugated paper sheet to a low speed tape conveyor in a sheet overlap system;

FIG. 2 is a top plan view of a corrugation suction box constructed in accordance with the invention;

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2;

FIG. 4 is a fragmentary sectional view taken on line 4-4 of FIG. 2; and

FIG. 5 is a profile view of portions of the overlap conveyor showing relative arrangements of parts.

Referring now to FIG. 1, a flexible sheet conveyor system is shown in which a first high speed tape bed 11 is arranged to receive sheets from a rotary cutter, not shown, and transport them to the position of a reject gate 12 over which good sheets pass to a second high speed tape bed 13. A low speed conveyor tape bed 14 is positioned below the projected extension of the tape bed 13. Additional elements of the tape transport can be seen in FIG. 5 and to facilitate an understanding of the invention FIGS. 1 and 5 should be considered together in the following description.

The high speed tape bed 11 travels on a set of spaced crowned collars 15, 17 and a shaft 16 to deliver cut sheets 18 to the position of the reject gate 12. The operation of the reject gate 12 to divert defective sheets to an alternate path is well known, and its operation will not be herein further described. When the reject gate 12 is in the position shown, the head end of sheets 18 is not diverted, and hence the sheets 18 pass over the reject gate 12 and on to the high speed tapes 13 of the second high speed tape transport system. The tapes 13 are supported on spaced crowned collars 21 and 22 which are supported for rotation on shafts 23 and 24, respectively, and separated laterally on the shafts. The spacing between the collars 21 is uniform according to conventional practice. For the collars 22, spacing therebetween is the same as the spacing between the collars 21 for the central three tapes, but except for these three central tapes, the collars are spaced, as at 25, somewhat less than the corresponding spacing between the collars 21. With each of these spaces 25 narrower than the corresponding space at the other end of the tape 13, the overall effect is to cause the tapes 13 to converge in the directlon of transport and this arrangement is indicated in exaggerated fashion in FIG. 1 in order to illustrate this feature of the invention. In actual practice the width of the spaces 25 may be less than the width of the spaces between the collars 21 by only a small percentage of the width dimension, and hence for a given installation the convergence of tapes 13 may not be readily perceptible to the eye. The progressively closer spacing of collars 22 provided by this width change relative to the spacing between the collars 21, however, and the corresponding convergence of the high speed tapes in the direction of paper travel provides ample sheet material between each adjacent pair of belts which can be utilized to form the corrugations in accordance with the invention. In this fashion the adverse effects of paper slipping across the tape is minimized and the degree of corrugation can be controlled when the machine is set up by initially establishing the amount of convergence which the spacing of the collars 22 determines.

Located between the top and bottom runs of the tapes 13 is a suction box 26, the details of construction of which will be described hereinafter in connection with FIGS. 2, 3 and 4. The box 26 provides a plurality of laterally spaced longitudinal supports 27 for the respective tapes 13 on the top run over the box 26. Between the supports 27 is positioned a plurality of baflles 28 which extend beyond the ends of the box 26 as at 29 into the recess between adjacent pairs of the collars 21 and 22. Suction is applied to the box 26 by means of a suction line 31 connected to one end of the box. A similar suction line 32 may be connected to a suction box 33 under the tapes 11, if desired, for control of the sheet 18 as it approaches the reject gate 12.

Referring to FIG. 2, a top plan view of the box 26 shows the arrangement of the tape supports 27 and the baffles 28 arranged alternately across the open top of the box 26. The baffles 28 extend at 29 beyond the side walls of the box 26 to project between the spaced pulleys on which the tapes 13 run. The extensions 29 thus provide a floor beneath the corrugated paper sheet that is running across the tapes 13 thereby preserving the suction force on the sheet beyond the actual perimeter of the box 26. An open slot 30 exists between the edges of the baffles 28 and the sides of the channel shaped support 27 for metering air flow as hereinafter described.

A suction hose 31 is connected to one end of the box 26 beneath the level of a horizontal bafiie plate 34 which extends across the open area of the box 26 spaced somewhat below the bottom surface of the baffles 28. The baffle plate 34 has a series of graduated size holes therein for distributing air flow from metering slots 30 formed between the edges of the baffles 29 and the skirts on the tape supports 27.

Further details of the construction of the box 26 with its tape supports 27 and baffles 28 and their relative arrangement for producing the metering slots 30 therebetween can be seen from FIGS. 3 and 4. In particular the length of skirts 35 and the width of baflie strips 28 can be altered to provide metering slots 30 of the desired area to permit the suction to be relatively independent of whether or not a sheet is passing over the tapes 13 thereby preventing a loss of corrugation if a sheet is being projected from the high speed tapes 13 toward the low speed tapes 14 without an oncoming subsequent sheet covering the upstream portion of the tapes 13.

The construction of the support and baflie structure indicated in FIG. 4 which covers the top of the box 26 may be by any suitable means, and a simple arrangement for this purpose can be provided by sheet metal formation of the alternate supports 27 and baffles 28 with suitable supporting connections to the walls and bottom of the box 26. Preferably, however, the entire top of the box can be fabricated of a hard, long wearing and non-corrosive material, such as stainless steel, with the alternate lands and valleys of supports 27 and baflles 28 formed therein with suitable width slots 30 cut out except for structural web joining members which would hold the pre-formed assembly together as a unit. The details of construction of this particular shape are not critical in the present invention and any suitable structure which performs the function of supporting the tapes and permitting suitable application of diiferetnial air pressure across a sheet traveling on the tapes will be satisfactory.

The operation of the corrugating system will now be described, particularly with reference to FIGS. 1 and 5. Sheets which arrive at the tape bed 13 over the reject gate 12 are immediately subjected to the differential air pressure created by the suction box 26 underneath the tape bed so that the head end of the sheet is immediately under positive control on the tapes 13. As the tapes 13 advance the sheet, a slight convergence of. all but the central three M tapes in the tape bed 13 moves edges 36 of the sheet toward the center of the tape bed thereby supplying ample material which in the regions between the supports 27 can be drawn down toward the baffies 28 to form the corrugated shape, indicated at 37. The top plan view of the sheet is thus trapezoidal and in continuous operation the actual appearance of a flow of the edges 36 of the sheet inwardly toward the center from both sides can be observed. As previously mentioned due to the proper proportioning of the metering slots 30, the corrugating force is effective on the sheet even as tail end 38 of the sheet approaches the end of the tape bed 13 at the collars 22. When the tail end 38 of the sheet is approaching the collars 22 at the end of the tape bed 13, the extensions 29 continue the effectiveness of the suction force on the sheet so that the sheet remains corrugated as long as it is on the tape bed 13, and hence the corrugations forward of the tail end of the sheet when it is in this position are maintained to stiffen the sheet for its projection upon and over the slow speed tape bed 14. As soon as the sheet is free of the tape bed 13, however, the nautral resiliency of the sheet and the weight of the sheet as it falls on the tape bed 14 tend to flatten the sheet into its normal planar configuration since the corrugations produced by the tape bed 13 are temporary in nature and do not produce a permanent crease or set in the sheet.

The application of the invention to the handling of flexible sheet material in various stages of processing will now be apparent from the detailed description herein given, and the invention, accordingly, is to be considered as including all such applications which come within the scope of the appended claims.

What is claimed is:

1. The method of stiffening traveling flexible sheets by producing temporary corrugations therein comprising the steps of transporting said sheets successively in a flow path, supporting sheets across the full width of said path at a plurality of laterally spaced longitudinally extending areas, applying differential air pressure across only portions of said sheets between the supporting areas in said path to depress portions of said sheets between said areas, and projecting the leading end of said sheet beyond said supporting areas in said flow path while maintaining corrugation of said sheet by said differential air pressure on t the trailing end of said sheet until the sheet has passed beyond said supporting areas.

2. The method of stiffening traveling flexible sheets by producing temporary corrugations therein comprising the steps of transporting said sheets successively in a flow path, supporting sheets across the full width of said path at a plurality of laterally spaced longitudinally extending areas that converge toward the center of said path in the direction of travel of said sheets, applying differential air pressure across only portions of said sheets between the supporting areas in said path to depress portions of said sheets between said areas, and projecting the leading end of said sheet beyond said supporting areas in said flow path while maintaining corrugation of said sheet by said differential air pressure on the trailing end of said sheet until the sheet has passed beyond said supporting areas.

3. The method of overlapping successive flexible sheets in a continuous stream flow of said sheets comprising the steps of transporting said stream at a first higher speed, projecting said stream at said higher speed above a conveyor traveling at a second lower speed, and applying differential air pressure to alternate longitudinal strips on each sheet while conveyed at said higher speed to produce longitudinal temporary corrugations in said sheet by displacing said strips relative to the portions of said sheet intermediate said strips.

4. The method of overlapping successive flexible sheets in a continuous stream flow of said sheets comprising the steps of transporting said stream on a plurality of laterally spaced longitudinal supports at a first higher speed, projecting said stream at said higher speed above a conveyor traveling at a second lower speed, and applying differential air pressure to each sheet while conveyed at said higher speed to produce longitudinal temporary corrugations in said sheet by displacing the portions of said sheet between said supports relative to the portions of said sheet on said supports.

5. The method of overlapping successive flexible sheets in a continuous stream flow of said sheets comprising the steps of transporting said stream on a plurality of laterally spaced longitudinal supports at a first higher speed, projecting said stream at said higher speed above a conveyor traveling at a second lower speed, and applying suction to the under surface of said sheets between said supports to produce longitudinal temporary corrugations in said sheet by drawing the portions of said sheet between said supports below the level of said supports.

6. An overlap conveyor for flexible sheets comprising a low speed conveyor for said sheets, a high speed conveyor having a plurality of laterally spaced substantially smooth endless tapes positioned to project said sheets above said low speed conveyor, said conveyors being aligned to form an overlapped stream of said sheets on said low speed conveyor, and means for applying differential air pressure on said sheets on said tapes for forming temporary longitudinal corrugations by deflection of the portions of said sheets between said tapes.

7. An overlap conveyor for flexible sheets comprising high and low speed conveyors arranged to produce an overlapped stream of said sheets on the low speed conveyor, said high speed conveyor having a plurality of laterally spaced substantially smooth endless tapes for delivering successive sheets to said low speed conveyor, a suction box having an open top positioned beneath said tapes, a plurality of spaced tape-supporting strips extending across the open top of said box in registry with said tapes, a set of bafile strips extending across the open top of said box positioned between said tape-supporting strips and below the tape-supporting upper surface thereof, the

edges of said tape-supporting strips and said baflle strips being spaced to define slots for metering air flow into said suction box, and means for maintaining air suction in said box sufficient to corrugate temporarily sheets transported by said tapes.

8. Apparatus according to claim 7 in which said laterally spaced endless tapes converge toward the center line of said high speed conveyor in the direction of travel of said sheets.

9. Apparatus for stiffening traveling flexible sheets comprising a conveyor having a plurality of laterally spaced substantially smooth endless tapes for transporting successive sheets, the plurality of spaced tapes having a total Width greater than the width of said sheets, and a suction box beneath said tapes operative only on the under surface of sheets between said tapes to draw portions of said sheets that are between said tapes down to form temporary corrugations in said sheets, said suction box extending along between said tapes to the end of said conveyor and operative to maintain the trailing end of said sheet corrugated until substantially the whole sheet has passed beyond said conveyor thereby maintaining the whole sheet corrugated until said sheet has left said conveyor.

10. Apparatus according to claim 9 in which said tapes converge in the direction of travel for said sheets by an amount corresponding to the lateral contraction of said sheets resulting from said corrugation.

References Cited by the Examiner UNITED STATES PATENTS 415,267 11/89 Hart 27176 2,925,167 2/60 Lindberg 271-69 X 3,051,296 8/62 Mertz 27174 X ROBERT B. REEVES, Acting Primary Examiner.

RAPHAEL M. LUPO, Examiner. 

1. THE METHOD OF STIFFENING TRAVELING FLEXIBLE SHEETS BY PRODUCING TEMPORARY CORRUGATIONS THEREIN COMPRISING THE STEPS OF TRANSPORTING SAID SHEETS SUCCESSIVELY IN A FLOW PATH, SUPPORTING SHETS ACROSS THE FULL WIDTH OF SAID PATH AT A PLURALITY OF LATERALLY SPACED LONGITUDINALLY EXTENDING AREAS, APPLYING DIFFERENTIAL AIR PRESSURE ACROSS ONLY PORTIONS OF SAID SHEETS BETWEEN THE SUPPORTING AREAS IN SAID PATH TO DEPRESS PORTIONS OF SAID SHEETS BETWEEN SAID AREAS, AND PROJECTING THE LEADING END OF SAID SHEET BEYOND SAID SUPPORTING AREAS IN SAID FLOW PATH WHILE MAINTAINING CORRUGATION OF SAID SHEET BY SAID DIFFERENTIAL AIR PRESSURE ON THE TRAILING END OF SAID SHEET UNTIL THE SHEET HAS PASSED BEYOND SAID SUPPORTING AREAS. 